Recently, a semiconductor device in which silicon carbide (SiC) is used as a semiconductor layer is widely used because it has a wide band gap and can operate at high temperature. In a conventional semiconductor device using silicon carbide, a metal layer is bonded over a semiconductor layer of silicon carbide, and an electrode layer is bonded over the metal layer. The metal layer is composed of, for example, titanium (Ti) as a main component, and the electrode layer is composed of, for example, aluminum (Al) as a main component.
Generally, a semiconductor device generates heat according to a flowing current. Additionally, in the case of the above-described conventional semiconductor device, since a melting point of aluminum of the electrode layer is the lowest among the respective layers, an allowable current that can flow from the electrode layer to the semiconductor layer is limited to a current value that is lower than the temperature at which the electrode layer composed of aluminum melts. Therefore, in the conventional semiconductor device, in order to increase such an allowable current, in place of aluminum, an electrode layer is composed of silver (Ag) having a melting point higher than that of aluminum (see, for example, Patent Document 1).